Pipe bending machine



July 20, 1965 L. LANG PIPE BENDING MACHINE 2 sheets-sheet 1 Filed Feb.18, 1965 14 19a 19h 1p 211 ,FIG.1.

July 20, 1965 l... LANG 3,195,339

PIPE BENDING MACHINE Filed Feb'. 18, 1963 2 Sheets-Sheet' 2 FIG.3.

United States Patent Office 3,135,339 Patented .any zo, 1965 s claims.(i. 'l2-sse) This invention relates to the shaping of pipes and likeelongated work pieces at ambient temperature, and more particularly to apressure-fluid operated pipe bending machine. An important object of theinvention is the provision of a machine which permits pipes to be bentinto complex shapes having small radii of curvature, bight portionsextending over arcs of more than 180, and a plurality of closelyadjacent bends extending in different planes. Certain automotive exhaustpipes and rope eye thimbles are typical of the shapes for the forming ofwhich the bending machine of the invention is of particular utility.

Another object of the invention is the provision of a bending machine inwhich the drive elements and associated motion transmitting members arelimited to a small area on one side of the working area proper of thebending machine so as to leave the working area free of obstructions asis necessary for the bending of complex shapes.`

A further object is the provision of a bending machine in which relativemovement of all bending tools is in a horizontal plane, and all bendsare therefore formed in this horizontal plane. This greatly facilitatesthe handling of a complex work piece.

Yet another object is the substantially uniform distribution of residualstresses generated in the work piece by cold Working so that closelyadjacent sections of the work piece may be subjected to bending indifferent directions without causing failure of the material underconcentrated residual stresses.

Other features and advantages of the invention will become apparent tothose skilled in the art as the disclosure is made in the followingdetailed description of preferred embodiments of the invention asillustrated in the accompanying drawing in which:

FIG. 1 is a side elevational View of a pipe bending machine of theinvention;

FIG. 2 shows the machine of FIG. l in top plan View, some portions ofthe structure being broken away better to reveal others;

FIG. 3 is a diagram of the hydraulic circuit of the bending machine ofFIG. l; and

FIG. 4 shows a detail of a modified bending machine otherwisesubstantially identical with that illustrated in FIG. 1.

' Referring now to the drawing in detail, and initially to FIGS. 1 and2, there is seen a housing 1 on which the operating elements of thebending machine are supported. The housing encloses the hydraulic pumpand other portions of the drive and control mechanism of the machinewhich will be described in more detail in connection with FIG. 3. v

An elongated lower guide plate 2 is mounted directly on the top of thehousing 1 and projects horizontally beyond the front face 3 of thehousing. An upper guide plate 4 is spacedly parallel to the lower plate2. The longitudinal end portions of the plates 2, 4 are connected byposts 5, 6 to which the upper plate 4 is fastened by screws 7. The upperplate 4 is relatively narrow as shown in FIG. 2. Theflower plate 2 has awider portion conforming to the top of the housing 1 and attachedthereto by screws 20. Its front end tapers, and the portion of the lowerplate 2 overhanging the front face 3 of the housing 1 has the same shapeas the corresponding portion of the upper plate 4.

A doubleacting hydraulic cylinder 8 is attached to the post 5 by screws10 which engage a ilanged end portion of the cylinder 8 remote from thecylinder head 11. The piston axially slidable in the cylinder S isintegral with a piston rod 12 .axially projecting from the cylinder 8and guided in a conforming bore of the post 5. The piston rod 12 istixedly attached to the head 15 of a coaxial single acting hydrauliccylinder 14. The front end of the cylinder 14 carries a block 16provided with a bore in which a piston rod 21 is guided axially inwardand outward of the cylinder 14.

Flat brackets 17a and 17b are respectively fxedly fastened to the topand bottom of the block 16, and thus to the cylinder 14 and the pistonrod 12. The brackets llare laterally in a forward direction. Guidemembers 18a, 1811 respectively attached to the brackets cooperate withguide rails 19a, 19b on the plates 2, 4 to guide the brackets 17a, 17bin paths parallel to each other and to the common axis of the cylinders8, 14.

The piston rod 21 has a forked free end portion 22 on which a transverseabutment rail 23 is fixedly attached. The rail 23 is elongated in ahorizontal direction perpendicular to the axis of the hydrauliccylinders. The front ends of the brackets 17a, 17b are connected by twopins 24 laterally spaced in opposite directions from the cylinder axis.The outer end portions of two bending rails 25 are respectively pivotedon the pins 24. The inner end portions of the rails 25 carry rollers 27arranged on pins 28 for travel on the transverse abutment rail 23.Several apertures 26 are spaced along the length of each bending rail 25for alternatively receiving the pin 24 as required by the bending workat hand. A dove-tail shaped guide bar 29 on the front face of each rail25 is slidably received in a conforming groove in the rear face of aslide 30. Longitudinal sliding movement of each slide in a laterallyoutward direction is limited by a stop 31 on the coordinated bendingrail 25. The front face of each slide 30 is formed with an openlongitudinal groove of approximately semi-cylindrical shape.

A bending mandrel 32 is releasably mounted on the post 6 by engagementof the post with a groove 34 in the front face 33 of the mandrel. Thearcuately shaped rear face of the mandrel 32 has an open, approximatelysemicylindrical groove in a common horizontal plane with the grooves ofthe slides 30 and facing the same.

The hydraulic system for the pipe bending machine is controlled by anoperator standing on the side of the machine visible in FIG. l. Apressure gauge 35 indicates the pressure in the cylinder 8 duringforward movement of the piston rod 12. The gauge 35 has a range fromzero to nine thousand pounds per square inch. Another pressure gauge 36having a range .from zero to three thousand pounds per square inchindicates the pressure in the cylinder 14 during forward movement of thepiston rod 21. Switch levers 38, 39 control solenoid valves in thehydraulic circuits of the cylinders 8 and 14 respectively. A hand wheel37 permits a pressure relief valve 50 for the cylinder 14 to be manuallycontrolled as will presently become apparent.

FIG. 3 is a conventional diagram of the hydraulic system. The hydrauliciluid is supplied by a motor driven pump 42 which draws the fluid from atank 44 through an intake pipe 43, and discharges it under pressure intopressure lines 40 and 48 respectively connected to control valves 41 and47. A safety valve 51 vents the lines 4t) and 48 to release excesspressure. The control valves 41, 47 are connected to the tank 44 byreturn lines 45, 49.

The valve 41 is connected to the front and rear cornpartments of thecylinder 8 by lines 45 and 40 respectively. VThe pressure gauge 35communicates with the line du'. A pipe 46 connects the cylinder 14, thepressure gauge 36, and the aforementioned manually controlled pressurerelief Valve 50 with the valve 47. As diagrammatically indicated, thepiston rod 21 is spring biased in a direction outward of thecylinder 1d.

In the position illustrated in 'FG 3, the valves dl, 47 block passage ofiiuid between the cylinders S, 14, and the pump 42. When the pumpoperates, the hydraulic luid is returned to the tank 44 in aconventional manner, not shown, through the safety valve 51.

Theswitch lever 38 has two operative positions for shifting the valvelll into a iirst` position in which pressure iiuid is admitted from thepump 42 through the lline 4d into the vrear compartment of the cylinder8, andthe front compartment is drained `through the line d5', and asecond position in which pressure fluid is admitted tothe frontcompartment and drained from the rear compartment. The actuatingsolenoids in electrical circuit with the switch of lever Sti areentirely conventional, and have not been shown. The sole compartment ofthe cylinder 14% is similarly arranged to be connected to the pump It?.or to the tank 4d when the lever 39 ismanipulated. The pressure reliefvalve '5u is normally set for the lower pressure desired in the cylinder14. n

The .afore-described apparatus is operated as follows: Pressure Huid isadmitted to the rear compartment of the cylinder` 8 and to the cylinder14 to move the bendingv rails from an inoperative position remote from`the mandrel 32 into'they position illustrated in fully drawn lines inFIG. 2 in which the slides 3@ andthe mandrel 32 engage a tubing lengthSftrom opposite sides, and the bending `rails Z5 extend longitudinallyin a common straight line parallel to thetransverse abutment rail 23.

The valve t7 is then setto connect the cylinder 1d' with the tank 44,and additional huid is admitted to therear compartment of the cylinder8, thereby further advancing the brackets 17a, l7b, and the hingedlyattached outer end portions of the bending rails 25 while the inner endportions of the rails 25 travel laterally away from each other on theirrollers 27' in abutting engagement with the rail 2li. The bendingoperation is lcompleted when the bending rails reach'the position 25aindicated in broken lines, whereby the length of tubing is bent into anarcuate shape asshown by the broken outline 52a.V The valve di isreversed, and the piston rod 12 is withdrawn inward of the cylinder 8until the apparatus revertsto its inoperative position.

PEG. 4 shows the bending tools of a modified pipe bending machine of theinvention otherwise closely similar to that illustrated in FIGS. 1 to 3.The front endof the cylinder 1d' carries a V-shaped bracket 17d. Twoauxiliary hydraulic cylinders 53 are respectively hingedly con nected tothe two forward ends of the bracket 17d by means of pins 55. A bendingrail 25h is ixedly attached to the piston 5d of each auxiliary cylinder53. The inner ends of the rails 25h are equipped with rollers 27b.

The free end of the piston rod 21' which is axially movable in thecylinder 14? carries a generally transversely elongated abutment rail23a whose lateral ends are bent in a forward direction. The rollers 27aengage the rail 23a for lateral movement thereon, and such lateralmovement is stopped when the rollers 27a reach the bent ends ot the rail23a.

The bending rails 25h are adapted to'cooperate with a mandrel `32ahaving a horizontal cross section which is defined by a circular arcsomewhat greater than 180 located opposite the rail 23a, and two flatsides extending from the ends of the arc and converging in a forwarddirection.y

The bending apparatus illustrated in FIG. 4 is operated iirst to clampthe tubing length 52 between the rails 25b and the mandrel 32a in aposition closely analogous to that illustrated in FIG. 2. The cylinder14'. is then connected to the return line leading to the storage tankfor hydraulic iiuid, and additional uid under pressure is admitted tothe high pressure or main cylinder cor-remasse sponding to the cylinder8, but not illustrated in FIG. 4. The resulting forward movement of thebracket 17d bends the tubing 52 about the arcuate rear face of themandrel 32a in substantially the same manner as described in connectionwith FIGS. 1 to 3. The auxiliary cylinders 53 are last supplied withpressure fluid through Avalves analogous to the valves 41, 47, to urgethe piston rods 54 outward of the cylinders. The tubing 52. is therebybent to conform to the dat sides of the mandrel 32a and to assume theshape of a rope thimble including a bight portion eX- tending over anarc greater` than 180. The ultimate position of one of the bending railsis indicated in broken lines at 25C, and the corresponding positions ofthe coordinated cylinder 53 and of a portion of the bracket 17d is alsoshown in broken outlines.

The bending'maohinerof the invention is very convenient for the bendingofautomobile exhaust tubes andof Y Asimilar' Complex shapesbecause/ofthe compactY arrangement of the bending tools and their driveswhich leaves the working area properV of the machine kuncluttered bydrive elements and by motion .transmitting members. There is littlerelative movement of the work piece. and

Y ofthe contacting portions of the bending rails so .that the bendingdeformation ofI all .portions'of the work piece is uniform. The residualstresses are therefore not concen-V trated in selected portionsY of the`work piece, and several bends `can be formed in closely adjacentlongitudinal portions of a tube at ambienttemperature withoutintermediate annealing.V The movement of the bendingrails from aposition adjacent vthe machine axis in a laterally outward directionduring. .the .bending operation enhances stretching of the outer ibersin the tubewhich is being bent, and reducesthe deformation of the innerfibers by compression. Itis therefore possible to bendV even openchannels of semi-circular cross section into thimbles for insertion inrope eyes and similar shapes.

Obviously, many modifications ,and variations of the present invention.are possible inthe light Vof .the above teachings. It is therefore to beunderstood that ,within the scope of the appended claims the inventionmay be practiced otherwise than as specilically described:

What I claim is:

1. A hydraulic device for bending pipes and like elongated workpiecescomprising, in combination:

(a) a support;

(b) a bending mandrel iixedly mounted on said support;

(c) a irst pressure-duid operated motor including a cylinder memberhaving an axis and a piston member axially slidable in said cylindermember, said cylinder member and ysaid piston member constituting afirst pair of members, one of said members of said pair being fastenedto said support for axial movement of the other member of said pair;

(d) a second .pressure-fluid Voperated motor including a cylinder memberhaving an axis and a piston member axially vslidable infthe cylindermember 'of said second motor, said piston member and cylinder member ofsaid second motor constituting a second pair of members axially alignedwith said rst pair, one member of said second pair being secured to saidother member of said first :pair for axial movement lof the other memberof Vsaid second pair toward and away from said mandrel; p

(e) an elongated bending rail having two end portions, one of said endportions beingsecured to said other member of one of said pairs, and theother end portion engaging the other'member of the other one of saidpairs; and

(f) valve means for separately controlling flow of a pressure uid to andfrom each' of said cylinder members.

2.. A device as set forth'in claim l, wherein` said one end portion ofsaid bending rail is pivotally secured to said other member of said rstpair.

3. A device as set forth in claim 1, wherein said one end portion ofsaid bending rail is pivotally secured to said one member' of saidsecond pair, and the other member of said second pair carries anabutment, said other end portion of said bending rail movably engagingsaid abutment.

4. A device as set forth in claim 1, wherein said cylinder member ofsaid first motor is fastened to said support, and said cylinder memberof said second motor is secured to the piston member of said rst motor.

S. A device as set forth in claim 1, wherein said one end portion ofsaid bending rail is secured to said other member of said iirst pair forpivoting movement, the device further including auxiliary pressure fluidoperated motor means mounted on said other member of said first motorfor actuating said pivoting movement.

6. A device as set forth in claim 5, wherein said auxiliary motor meansinclude an auxiliary cylinder member pivotally attached to said othermember of said rst motor, and an auxiliary piston member slidable insaid auxiliary cylinder member, said bending rail being attached to saidauxiliary piston member.

7. A device as set forth in claim 1, wherein said other end portion otsaid bending rail movably engages said other member of said other pair,and stop means on the last-named other member for limiting movement ofsaid bending rail.

S. A device as set forth in claim 1, wherein said axes extend in ahorizontal direction.

References Cited by the Examiner UNiTED STATES PATENTS 2,880,779 4/59Migori 153-33 2,887,141 5/59 Lang 153-38 2,892,479 6/59 Holsclaw a153-33 2,938,564 5/60 Rhodes 153-38 3,017,915 1/62 Walrnsley 153-333,073,372 1/63 Lang 153-38 FOREGN PATENTS 1,240,595 8/60 France.

CHARLES W. LANHAM, Primary Examiner.

1. A HYDRAULIC DEVICE FOR BENDING PIPES AND LIKE ELONGATED WORK PIECESCOMPRISING, IN COMBINATION: (A) A SUPPORT; (B) A BENDING MANDREL FIXEDLYMOUNTED ON SAID SUPPORT; (C) A FIRST PRESSURE-FLUID OPERATED MOTORINCLUDING A CYLINDER MEMBER HAVING AN AXIS AND A PISTON MEMBER AXIALLYSLIDABLE IN SAID CYLINDER MEMBER, SAID CYLINDER MEMBER AND SAID PISTONMEMBER CONSTITUTING A FIRST PAIR OF MEMBERS, ONE OF SAID MEMBERS OF SAIDPAIR BEING FASTENED TO SAID SUPPORT FOR AXIAL MOVEMENT OF THE OTHERMEMBER OF SAID PAIR; (D) A SECOND PRESSURE-FLUID OPERATED MOTORINCLUDING A CYLINDER MEMBER HAVING AN AXIS AND A PISTON MEMBER AXIALLYSLIDABLE IN THE CYLINDER MEMBER OF SAID SECOND MOTOR, SAID PISTON MEMBERAND CYLINDER MEMBER OF SAID SECOND MOTOR CONSTITUTING A SECOND PAIR OFMEMBERS AXIALLY ALIGNED WITH SAID FIRST PAIR, ONE MEMBER OF SAID SECONDPAIR BEING SECURED TO SAID OTHER MEMBER OF SAID FIRST PAIR FOR AXIALMOVEMENT OF THE OTHER MEMBER OF SAID SECOND PAIR TOWARD AND AWAY FROMSAID MANDREL; (E) AN ELONGATED BENDING RAIL HAVING TWO END PORTIONS, ONEOF SAID END PORTIONS BEING SECURED TO SAID OTHER MEMBER OF ONE OF SAIDPAIRS, AND THE OTHER END PORTION ENGAGING THE OTHER MEMBER OF THE OTHERONE OF SAID PAIRS; AND (F) VALVE MEANS FOR SEPARATELY CONTROLLING FLOWOF A PRESSURE FLUID TO AND FROM EACH OF SAID CYLINDER MEMBERS.